Because while the games between the sides haven't been great recently, the Portuguese and the German are two of the most entertaining coaches around, for different reasons.

Unlike the case with Mourinho and many other top bosses, there hasn't exactly been a war of words between the pair, but their exchanges over five years of fixtures do offer an insight into their relationship.

Take it away, fellas.

October 24, 2012, after Borussia Dortmund's 2-1 Champions League group stage victory over Mourinho's Real Madrid

He;s behind you Jose! (Image: Martin Rose)

Mourinho: "This group is very tough. Some of them are a joke but this is the group."

November 6, 2012, after a late Mesut Ozil free-kick secured Real a point from a thrilling 2-2 draw, which featured a contentious disallowed goal from Gonzalo Higuain

All smiles... for now (Image: Dennis Grombkowski)

Klopp: "I was told it (Higuain's goal) wasn't offside. Overall it was a lot of fun and a very intensive match.

"We forced our opponents to all kinds of things that they weren’t necessarily willing to do. It was a great game. I'm sure we will still remember this game in 10 years' time."

Mourinho: "We scored three goals! It was a great game. As a fan I would prefer to see a game like this than the games in some other groups that are like Europa League games.

"We committed two bad defensive errors. When you play against good teams and you make mistakes, they kill you.”

April 24, 2013, after four Robert Lewandowski goals earned Dortmund a stunning 4-1 victory over Real in the first leg of the Champions League semi-finals

Mourinho: "Dortmund were the best team by far. Many of our boys didn’t perform, many didn’t have a good night. They were stronger collectively and in every individual duel.

"We had so many difficulties. We couldn’t cope with their counter attack and their transition. When you lose and you deserve to, it is not so hard to take.”

April 29, 2013, a day before the second leg, and the first sign of a little friction between the pair

"Me? Talking too much?!" (Image: Juergen Schwarz)

Mourinho: "I have said a little bit about Dortmund and that's enough. Since the day of the draw, Klopp talks every day."

Klopp: "Mourinho says I speak too much? That's what one of my teachers used to tell me. I don't care, I don't think about this. "(Is it mind games?) I'm not intelligent enough to understand what it should be. But it's no problem, now I'll shut up, and everything is okay."

April 30, 2013, after Real attempt a valiant fightback in the second leg, winning 2-0 but losing 4-3 on aggregate

Mourinho couldn't put Klopp in the shade (Image: Mike Hewitt)

Klopp: "Dortmund apparently are an all-inclusive club, so we always make things exciting, one way or another."

Mourinho: “In football you win or you lose, and we could have won this tie. Today we were a team, with character and desire, and we could have done it.”

October 31, 2015, after Klopp's Liverpool beat Mourinho's Chelsea 3-1 at Stamford Bridge in just his third Premier League game in charge

Klopp: "I feel for him (Mourinho). He's a great coach. I don't think anyone in this room doubts he's one of the best in the world.

"Things like this happen. I had a similar situation at Dortmund last year. The good thing was no one in the club was in doubt of my situation. I feel for him of course, but it's work."

Mourinho: " I can't express my feelings in any way at all. You are not just here to interview me. You are also here to see the game. What I see from my players was good until the moment they felt it was impossible to do better.

December 18, 2015, after Mourinho's sacking as Chelsea manager

Klopp: "It is a sad situation that such a successful relationship between Mourinho and Chelsea ends like this.

"I wish Jose all the best. It is good to have a bit of rest as he has worked constantly for many years at a high level."

October 16, 2016, before Liverpool entertained Manchester United at Anfield

He obviously found that funny (Image: Getty)

Klopp, on suggestions that Mourinho had lost some of his powers: "Bulls***!"

Mourinho, on his opponent's touchline behaviour: " I'm on the touchline to try and coach.. I'm not on the touchline... doing this (frantically waves arms)."

October 17, 2016, after an ultra-defensive United ground a goalless draw

Klopp: "I am not too happy. The game from the first second was very hectic and maybe that was what Manchester United wanted and we didn’t want, maybe it was more for their advantage."

Mourinho: "It is a result that stops a direct opponent getting three points at home, so not a bad result.

“We stopped them playing but they also did very well from the defensive point of view. They played Can and Henderson for some reason and they did that for 90 minutes when they normally project more players in attack. They were very cautious."

January 15, 2017, after United and Liverpool played out an entertaining 1-1 draw at Old Trafford

Klopp: " In the end period of the game when United started playing long balls after 80 minutes of high intense football it is really hard.

"It is so intense. They play long balls, it was a wild game. There was a lot of action in the last few minutes. We were here to win the game, which is why we we are not 100% satisfied."

Mourinho: "They were clever. They took their time, they know how to play football and control the emotions of the game. They knew they would be in trouble in the final few minutes.

"We were the team that attacked and Liverpool were the team that defended - let's see if the critics are fair."

March 9, 2018, before this weekend's meeting at Old Trafford

Will Klopp go on the attack at Old Trafford? (Image: Liverpool FC)

Klopp (on Mourinho's tactics): "I t’s easy to sit at home and think Liverpool score like they want and United didn’t score that often, so that’s the thing, but there are reasons why they have two points more than us. We want a result, that’s the only thing we go there for.

"It’s football, they’ll defend whenever they want to defend, we have to try and create something. If they attack, we’ll need all our legs to defend these situations."